Flexible casing for oil wells



oct. 4, 1921.'

- W. A. TROUT FLEXIBLE CASING FOR OIL WELLS A Filed Oct. 6. 1924 l Patented Oct. 4, 1927. u,

y UNITED STAT WILLIAM A. TROUT; or Los ANGELES, CALIFORNIA, AssIG'N'oa 'ro4 Eneco Eumex a PATENT-formes.-

EQUIPMENT'COMPANY, A CORPORATION 0F CALIFORNIA.

FLEXIBLE cAsING ron oIL wE'LL.

Application illedfOctober 6, 1924.- VSerial No. 741,878..

My invention relates to the art of drilling wells and may be appliedA to both oil and water wells.

It has been the general practice for a considerable period to provide metal casing for both oil and water wells, seamless tubing threaded on each end provided with screw couplings being commonly used. Such casing can be readily inserted in the well and4 is watertight under pressure when so installed. Casing of this type is generally known as screw casing.

It has been the practice ,for some time in water wells, and in some cases in oil wells,

to insert in the hole, particularly at the beginning of the well, what is known as stovepipe casing, this casing being made up of sheets of steel rolled into cylindrical form andv securedv together by rivets or otherwise, as it is installed in the well, to form a continuous casing. Stovepipe casing has been principally used in the oil industry to hold out rocks, gravel and other loose formations which are encountered near the surface 'of the ground before the more solid formations vare encountered. When used in oil wells for this purpose, and as used in water wells, it is not necessary that the stovepipe casing be watertight, its purpose being merely to prevent sand, gravel, or other loose material from falling into the well. Such stovepipe casing has certain very great advantages over screw casing, in that it 'is cheaper to manufacture, but it has the disadvantage that it cannot be readily handled by the usual types of elevators used in oil well drilling, and the very great disadvantage that it cannot be used to shut olf the surface water. x,

It is an object of my invention to provide a flexible casing built up from sheets of steel in a somewhat similar manner to the stovepipe casing which. when completed, will be watertight and which will be soconstructed that it can be readily handled in a manner similar to screw casing.

Further obejcts and advantages will be made evident hereinafter. 'l

Referring to the drawings which are for illustrative purposes only, y

Fig. 1 is a perspective view partly in section showing the casing in the process of assembly.

Fig. 2 is a perspective view of a clamping ring.

' 32 of the sheet 30 are pulled together Fig.V 3 is a perspective view partly in section of the upper portion of a joint of such casing prevlous to its being secured to an adjacent joint.

Figs. 4, 5 and 6 are sections through various forms of joint which may be employed in this casing. Fig. 7 is a view showing aportion of the completed caslng and the method of handling same.-

used for insuring complete galvanization.

My novel formof casing is made up of these cylinders being formed of shortv lengths of sheet steel rolled into cylindrical form. The sheets 10' forming the inner cylinders 11 are each joined at their meeting edges- 16 by welding. The sheet metal at each end 17 of each of the innercylinders 11 is bent backen itself, as shown, preferably whilethe sheet is flat and prior to its being rolled into a cylinder. Each of the inner cylinders thus terminates in av rolled edge, the metal turned back forming an annular ridge ateach end of the cylinder. y l

The annular ridges 14 on adjacent inner cylinders 11 are then placed end to end and a split clamping ring 20 is secured therearound. This ring has inwardly rojectin lips 21, and whensprung over and 1n place around the ridges 14, it holds them r1g1dly in alignment and against axial displacement. The clamping ring 20 is then welded along its edges 22, which are held clampe ntogether by clamping means, not shown. l

This ring may be made, as shown at in Fig. 5, without the lips 21 being formed of thicker material than the cylinders 11 and 12, thus forming a stifening or strengththe ridges 14 andthe clamping rin 20 or form and sprung over the joint formed by 90. Each of the sheets 30 1s provi ed near its center with a rolled ridge 31 of suiiicient axial length and diameter to clamp snugly about the clamping ring 20 when the ed es suitable clamps, not shown, the cylinder si; formed fitting closely over the inner layer 11 of the casing. `The edges 32 'are then v 65 I Fig. 8 is a section showing the hmethod Welded and theclamps removed. It will thus be seen .thatthe rings and the outer sheets -30 ser e to lock the inner cylinders 11 tocgletlier- In some cases I omitthe ring 20,

spending wholly upon the ridges 31 which fit tightl over the rldges 14 for holding the inner cy inders together. The sheets forming the outer'c linders may be bent back on themselves, as s own in Fig. 6, to` form rridges-35 at each end, or the `may be left flat, as shown in Fig..1. If le t fiat, the edges 36 of-adjacent outer cylinders abut against each other and 'may be welded together.v If bent back, as shown in 1g.v 6, the ridges 35may be locked together with l a locking ring 38.

mately-in the center of the outer cylindersl 12, being inside the ridge 31. The outer and inner cylinders, 11l and 12,-being of the same length, the joints of the outer cylinders 12 come at about the center of the inner cylinders 11. l'

The assembled joint of casing as built in the shop consists of one less outer cylinder than the number of inner cylinders, so that at each end' ofl the fabricated joint ,the last outer cylinder 12 terminates at a point 50, as shown in Fig. 3, Vand approximately 4onehalf of an inner cylinder 51 projects there- The completed 2O or 30 foot joint of casing is then immersed in a galvanizing bath,

lfor the purpose of protecting it against rust locking its component parts together, and

rendering it fiuidtight. For the purpose of lfacilitating galvanizing, I provide, preferably in the Irouter cylinders 12. depressions which are spaced a few inches apart and which hold the inner c linders 11 and the outer cylinders 12 apart` eavingan openingv 61 therebetween, as shown in Fig. 8. This opening 61 is of substantially uniform thickness and in the galvanizing bath is filled with spelter which adheres toboth the inner cylinders 11 and the outer cylinders 12, forming a continuous bond and eifectually closin cracks o r joints in either series of cylin ers. i l

The completely fabricated and galvanized joint is then ready for installation in the well. The ridges 31, as shown in Fig. 7,

vform collars against which an elevator 70 can abut and means by which thecasing can be readily lifted.

The first joint being inserted in vthe well, it is supported on slips, not shown, with its upper end standing vertically, as shown in Fig. 3.

A second joint of casing can then be lowered until its lower end abuts on Vthe upper end of the first joint, a previously galva- 'nlzed ring 20 in its open position, as shown 4in Fig. 2, and a prevlously galvanized outer cylinder 12 in its open position, as shown in Fig. 1, being. first slippedv over either the first or second joint.

The ring 20 -is then clamped over the adjacent ends of the first and second joints,

`and its meeting edges 22 are welded toring l20 may in some cases be omitted, the

outer cylinders 12 acting as locking means for the inner cylinders 11.

If itl is desired to use the form `or" construction shown in Fig. 6, a locking ring 38 is then placed at each end of the outer cylinder 12, locking it to the outer cylinders al-- ready in place and 'galvanized into the first and second joint. The locking rings 38 may then be welded. Usually, however, the edges 36 of the outer cylinders 12 are not rolled and this edge on the outer locking cylinder is welded at each end to the outer cylinders of the first and second joints.

The first and second joints being joined as just described by a ring 20 and an outer cylinder 12, they form a continuous pi e which can be lowered into the well until t e upper end of the second joint is in position to e similarly joined to a third joint. The process of adding joints and lowering is continued until the ufinished casing is landed on bottom atthe desired depth.

v The casing so produced has certain rather obvlous advantages over ordinary screw caslng. It may be-fabricated from fiatv sheets near the polntof utilization. Not only are the fiat sheets cheaper to produce and easier to transport and handle, than the finished pipe, but they arenot as liable to be injured by such transportation or handling.

lIt is also possible to use sheet steel having special characteristics, such as excessive hardness or toughness,- which cannot be obtained in screw casing due to its process of manufacture.

The finished casing can also be made in considerably lighter Weights per running foot than screw casing,'due to the necessity of providing a certain rigidity in screw casing if its joints are to .be made effective. The lighter casing made by my method is not only cheaper but it is much more fiexible than screw casing and it readily accommodates itself` to irregularities in the well bore, which would prevent the installation of or would seriously injure such screw casing.

My casing is also of substantially uniform strength `throughout its length, the method nular shoulder; and anouter layeir of sheet of securing the joints together in the field being much stronger than the common method of joining screw casing. It 1s also of smaller outside diameter for a given bore, the joints shown in Figs. 4 and 6 conslstmg of only four thicknesses of thin sheet metal in place of the thick collars used on screw casing. By omitting the clamping r1ng 20, and depending whollyupon the outer cyllnder 12 as a locking means, as has been previously explained, my casing is only one thickness of sheet metal thicker at the joints than elsewhere. The joints being only slightly larger than the body of the casing, it slips readily into even a tight hole lin which the collars of screw casing might catch and hang. Since the friction on the outside of my casing is small, due to its nearly uniform outside diameter, I am able to install itin holes into which screw casing Acould'not be forced, and what is equallyl as important, I can pull this casing from such holes under conditions which would lock screw casing beyond hope of recovery. As a result, a smaller hole can be drilled for a' given internal diameter of casing, where my casing is used, than would be safe were screw casing used. This small diameter of hole results in considerable saving in drilling expense.

By making a casing which is reinforced at short intervals with'` annular ridges 31, I provide a casing that will hold its shape and resist pressure much better than screw casing of the same weight per foot.

It is very common for screw casing, particularly in the larger diameters used in starting an oil well, to become split due to strains to which it may be subjected, to its lack of flexibility, and to flaws in the casing, particularly along the Welded seams. If, as is commonly the case, this split is not discovered until after the casing is permanently set in the Well, it ordinarily cannot be repaired but the Well must be recased with a smaller diameter of casing at very great expense. Since my casing is thinner and made up of two layers, it is highly iiexible, giving readily under conditions that would split screw casing. Being rolled in fiat sheets, the metal is homogeneous and will not split; or should a' sheet be defective, the break or tear -will not extend to the other thicknesses of metal comprising the casing, which ismade from an entirely different and entirely lindependent sheet.

I claim as my invention:

l. Astovepipe casing for Wells comprising: an inner layer formed of axially aligned sheet metal sections .disposed in abutting relationship and having body portions, the

l abutting ends of said sections each being bent back along and in close contactwith said body portions to form an external an metal embracing the abutting end portions of adjacent inner sections including .opposed v annular locking ridges engaging said shoulders to lock said inner sections againstaxial' separation. l

2. A stovepipecasing forwells comprising: an inner layer formed of axially aligned cluding opposed annular locking ridges closely engaging said shoulders to lock said inner sections against axial separation. v

3. A stovepipe casing for wells comprising: an inner layer formed of axially aligned ,sheet metal sections 'disposed in abutting re lationship and 'having body portions, the abutting ends, of sai sections each being vbent back`along and in closecontact with said body portions to form an external annular shoulder; and an outer layer of sheet metal embracing the abutting end portions of adjacent inner sections including opposed annular locking ridges closely engaging said shoulders to lock said inner sections against axial separation, said outer layer pro 'ding a horizontal annular abutment adapt d for engagement by a well casing elevator.

' 4. A stovepipe casing for oil wells comprising: an inner layer formed of axially aligned sheet metal sections disposed in abutting relationshi and having body. portions, the abutting ens of said sections each being bent back along and in close contact with said body portio to form an annular external shoulder' a filler member surrounding said abutting bent ends ofl adjacent inner sections; and an outer layer of sheet metal enclosing said bent ends and said filler member, said outer layer including an annular ridge which encloses said bent ends and said filler member.

5. A stovepipe casing for wells comprising: an inner layer of sheet metal made up of short inner sections; a turned rim on each end of each of said inner sections, said turned rims abutting against each other; a filler member situated outside said rims; and an vouter layer of sheet metal fitting over and 4 sheet metal sections disposed in abutting re-` so.. j

locking ridges litting over said rims for .securing the rims together. v

6. A stovepipe casing for wells comprising an inner layer of sheet metal made up of short inner sections; a turned rim on each end of each of said inner sections, said turned rims abutting against each other; a filler member situated outside said rims; and an outer layer of sheet metal fitting over and contacting said inner layer ineludmg annular locking ridges fitting over said rims and enclosing said filler member for securing the I rims together.

7. A stovepipe casing for oil well use com- Pri'sing: an inner cylindrical member, said lnner cylindrical member being composed of cylindrical sections; turned cylindrical rims 1Q on the ends of said sections, the rims of adjacent sections abutting; and an outer cylindrical member, said outer cylindrical member entirely enclosing said sections including ann'ular ridges which embrace saidv abutting rims.

In testimony whereof, I have hereunto' set my hand at Los Angeles, California, this 30th day of September, 1924.

WILLIAM A. TROUT. 

